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PAR Live Review: Alto Professional Stealth Wireless System for Active Loudspeakers

Simple ideas are often
the best solutions. Alto Pro’s Stealth Wireless eliminates the need for cable
between any traditional sound source and powered speaker, opening an attractive
array of placement options for gigging musicians, live venues,
houses-of-worship, etc.

I first saw Stealth Wireless
this past June at InfoComm 2013, at the Alto Professional booth. Billed as a
simple way to bypass cables between a mixer and loudspeakers, at least a dozen
specific applications came to mind as I held the pre-production model in my
hand. Since then, Alto Professional has ramped up production on Stealth
Wireless and it is shipping now, at $399 street.

Features

The Stealth Wireless package
consists of one Transmitter and two Receivers with three power adapters (12V
DC, 300 mA) for each, plus mounting accessories: two M10 screws (for mounting
Receivers to fly points on powered speakers) or “hook and loop” Velcro-style
strips (for mounting Receivers on virtually any surface).

The Transmitter is switchable
between Mono and Stereo, sending one or two channels of audio to every Receiver
in range (reportedly up to 200 feet away) and on the same channel (one of 16
UHF channels). Transmitter features include two balanced/unbalanced
XLR/quarter-inch TRS inputs, dual antennas, a red LED signal clip indicator
(flickers at -4dB before and glows solid at clip), press/hold-style Channel
Select button and LED display, and two rotary input trim knobs. Frequency
response is a sufficient 50 Hz - 17 kHz, +/- 3 dB. Unit dimensions are 6.3 x 5
x 4 inches.

Each Receiver—a small 4.6 x
2.8 x 1.3 inches—includes an antenna, Power button, XLR output, AF Indicator
LED (glows when signal is recognized), RF Indicator LED (glows when signal is
received), Power Indicator LED and a press/hold-style Channel Select button. On
the Receiver’s side, a Left/Right Selector and Squelch (for setting a noise
limit) are available.

In Use

Out of the box, I recognized
that Stealth Wireless couldn’t be much easier to use. For that reason, I first
employed it per request from a local church needing to simply provide stereo
audio from the pulpit to a sunday school building next door, the location of
the nursery and children’s church services. The pastor couldn’t have been more
relieved when I told him I had a possible inexpensive solution that wouldn’t
require them to run any more cable, as the church’s classrooms and needs
frequently change.

Admittedly, I was a bit
worried about the distance and barriers between where the Transmitter and
Receivers would reside—the Transmitter within a room in a rock-and-mortar
church, which would need to reach Receivers slightly more than 100 feet away
and through the other building’s cinderblock and brick exterior to two separate
rooms and powered speakers. Long story short, it worked: over a span of three
weeks and in a variety of speaker placement locations within the separate
building, no notable interference was heard, and, from my own observations,
both loudspeakers sounded much as if they were receiving cable-delivered
balanced XLR inputs—other than a slightly higher noise floor that wasn’t overly
distracting or offensive.

Next, I employed Stealth
Wireless at a club gig with a four-piece cover band, smack dab in the middle of
a downtown/metro setting on a Friday night, thus ripe for potential wireless
interference. Using two main powered loudspeakers in the setup, I placed one
monitor as a main room loudspeaker, then another at the back of the club, in an
additional bar area at a lower volume. Here, the Mono option on the
Transmitter’s front panel was extremely useful, as we were working with only
one main loudspeaker per area, though the musicians were monitoring in stereo. I
easily found an interference-free channel, which worked ideally for the band
during a three-hour/three-set show.

Summary

Alto’s Stealth Wireless may
not win an award for our industry’s most sexy new product, but I found it can
often answer the question, “How could I more easily distribute this audio?”
While not a permanent solution, Stealth Wireless is an ‘easy to use’ one,
potentially bridging many gaps in a variety of live sound settings.